To meet greenhouse gas emissions goals for 2050, we’ll need to change our eating habits, researcher Zak Accuardi explains
If you want to significantly reduce your carbon footprint, it might be time to rethink your diet.
Agriculture is responsible for enormous quantities of greenhouse gases. Livestock production alone accounts for 15 percent of all human-produced emissions globally , according to the U.N.
But not all foods are carbon-emitting equals. By making informed choices at the grocery store, you can reel in your personal contributions to our planet’s rapidly changing climate.
Zak Accuardi recently completed a fellowship at Project Drawdown , where he focused on the impact of dietary choices on climate change.
Project Drawdown is a California-based coalition of more than 200 researchers, scientists, policymakers, students, activists and business leaders from around the world, assembled to research technological and social solutions to climate change.
“Climate scientists have done a really good job of highlighting what will happen if we don’t act to reduce our emissions,” Accuardi said. “But nobody has done a systematic accounting of what could happen if we use all of the knowledge we already have to apply technologies and policies – and individual behavior changes – that we know will have some kind of an impact.”
This is a gap Project Drawdown intends to fill by disseminating research such as Accuardi’s to communities around the world.
FURTHER READING: 'Drawdown': The plan to save the world from climate change
Accuardi is a Portland native who specializes in sustainable urban development. He earned his undergraduate degree in environmental engineering from Columbia University and his master’s in technology and policy from Massachusetts Institute of Technology, and he’s served as a consultant to World Bank – not a bad resume for a 26-year-old. Today he’s a research analyst at TransitCenter in New York City.
Accuardi pored over available data on various foods to determine how they rank in terms of greenhouse gas emissions. He not only examined emissions from an item’s production, but also from processing, cleaning and transporting, and even whether or not it was refrigerated at the grocery store.
“All those activities have an environmental impact that we need to understand in order to fully account for the impact that food has on the environment,” he said.
During an interview with Street Roots, Accuardi explained what a low-carbon diet looks like, what foods have the greatest impact on climate change, and innovations taking place in agriculture that might help us keep some of our favorite foods on the menu.
Emily Green: How much of an impact does our diet have on climate change?
Zak Accuardi: Estimates vary, but from the Intergovernmental Panel on Climate Change data, which is the leading authority on climate science, roughly 20 percent of our total greenhouse gas emissions come from either agriculture or livestock production and the changes in land use, which is often shorthand for deforestation. Twenty percent may or may not sound like a lot, but that’s more than the entirety of the transportation sector – so cars and airplanes and freight transportation and boats. That’s more than the entirety of the building sector, so all of the electricity and heating that we use in buildings, and that’s nearly as much as the entirety of the industrial sector – so everything that we make.
The 20 percent number, I find to be interesting, because a commonly articulated emissions reduction goal is that we need to reduce 80 percent of global emissions by the year 2050, so to me, this demonstrates that some very substantial behavior change will be necessary because even if we achieve complete carbon neutrality in every other sector – in electricity, building, heating, industrial energy use, transportation, fuel – if we’re able to completely eliminate the emissions from all those sectors, we would still have to reduce our greenhouse gas emissions from agriculture just by virtue of the fact that population in the world is going to continue to grow between now and 2050.
Some of the reductions we need to achieve will be possible by changing agricultural practices and livestock production practices, but that only gets us so far. I don’t think anyone believes that we can achieve complete carbon neutrality in all of those sectors by 2050, so it’s clear that we will need to make some substantial changes in our personal lives around diet.
“The most important dietary changes Americans can make to reduce their environmental impacts are eating less beef and lamb, substituting as much plant-based protein for animalbased protein as possible, not overeating, and buying the right amount of food in the first place so you don’t need to throw so much away.” — Zak Accuardi
E.G.: Were there any particular countries whose diets were creating more carbon emissions than others?
Z.A.: Absolutely. The tendency is wealthier countries tend to create higher emissions, and in part that’s because affluence correlates with increased consumption of food products like beef, which is among the highest emissions producing. There are exceptions to that. Some regions have fundamentally different food availabilities, and many people are not even able to access sufficient nutrition to maintain their own personal health – the implications being it can be harder to compare countries side by side, because if you wanted to compare the U.S. with Ghana, for example, then you’re looking at completely different context, completely different agricultural systems, totally different traditions around food and what is eaten.
E.G.: Are there any countries where cultural aspects might make encouraging a lower-carbon diet more of a challenge?
Z.A.: It can go in both directions. For example, one of the questions I had was: What is the existing adoption rate of vegetarianism or veganism internationally? And I mostly found there is very little data on that question, if any, that’s really reliable. To the extent that I found anything, it was that India has, perhaps by far, the highest incidence of vegetarianism, and that’s for cultural and religious reasons, and yet at the same time, India is one of the countries that the Food and Agriculture Organization of the U.N. projects to increase its meat consumption most dramatically over time. I think that’s because in India – and the same would be true in China and other rapidly developing countries – as they get more wealthy, they are projected to increase their meat consumption.
E.G: I was surprised by how much more emissions come from beef than anything else. Can you explain how beef is creating so much greenhouse gas?
Z.A.: Beef and lamb are ruminant animals, which is the technical term for multiple stomachs. And they, alongside sheep and goats, need to eat a lot more raw feed in order to gain an equivalent amount of body mass, and end up producing a lot more methane and manure as a result. They don’t process the food that they eat very efficiently in the first place, and that biological food processing is the reason they produce so much methane. So any country that has high beef or lamb consumption is going to tend to have a higher emissions share.
E.G.: What’s the main source of emissions when it comes to cows? Is it all the land needed to grow their food, or is the methane that they produce with their solid waste?
Z.A.: It’s a combination. Brazil is a major beef-producing country, and many, many acres of previously forested land have been cleared to create room for livestock production, and you see that in countries around the world. Forests are cleared to make room for agriculture, but especially livestock.
Methane production through the cow’s flatulence is also a very substantial contributor. Methane is a much more powerful greenhouse gas than carbon dioxide, by a factor of 34 times.
E.G.: Is there any way to keep cheeseburgers on the menu?
Z.A.: There are some ways folks are exploring reducing the emissions from beef production, including adding supplements to cattle feed during production. There are synthetic additives, but also natural ones, like oregano, which when added to cow feed has been shown to basically increase the efficiency of their digestive processes, thereby reducing the amount of methane that’s produced.
You can actually breed for more efficient production. By choosing cows that have been measured to produce less methane over the course of even just a few generations, you can improve, pretty substantially, the efficiency, and therefore reduce emissions from beef production.
There is a theory that has real potential to it – raising all of your cows under a giant tent, basically, and capturing the emissions through a tube at the top where the methane would gather, so basically finding ways to capture that methane and either reuse it or even just flare it, which means burn it, not for the purpose of heating anything, but for the purpose of converting that methane to carbon dioxide, which potentially reduces the greenhouse gas impact.
I have also heard that some people think there are ways to raise beef that can actually balance or reduce greenhouse gas emissions, and that would be through a lot of creative land use and grazing practices that would also include some potential crop rotations and lots of very advanced soil management practices. But I think that needs to be explored a lot more before we start celebrating.
E.G.: How is it that local beef can emit more greenhouse gases than even fruit flown from halfway across the world?
Z.A.: Fruit and vegetables that are coming from far away are often shipped by boat, rather than by plane, and shipping by water, over thousands of miles, can be a much lower impact than shipping fruits and vegetables, even very short distances. So in Portland, for example, if you are getting produce from Northern California, shipped by truck, that might be a higher greenhouse gas impact from the transportation than getting bananas from Central America by boat. And that’s a common misconception. Eating locally is generally a good idea, in terms of carbon emissions, but usually not as big as folks think. The estimate from scientific literature is that eating produce that’s produced locally instead of from far away reduces that food’s greenhouse gas impact by about 5 percent. This only applies to an apples-to-apples – pun intended – comparison, and wouldn’t apply to something like bananas, that don’t grow in the Pacific Northwest, for example.
E.G.: That’s really surprising.
Z.A.: Yeah, it is really surprising, and it’s counter to a lot of the conventional narrative. Also surprising is that producing organic produce can actually be more carbon emission intensive than so-called conventional or non-organic produce – in some cases. One of the really big challenges for consumers is that it’s very hard – if not in many cases impossible – to know, if you’re choosing one carrot versus another carrot or one type of fish versus another, what the relative impacts are. That’s a huge barrier to consumers making informed choices about their diet. That makes it hard in some cases to give really descriptive guidance on making food choices. It’s sort of restricted to knowing the more general truths, and this general hierarchy, which the graph in the climate report (City of Portland’s 2015 Climate Action Plan ) is intended to convey: that greens and starchy vegetables tend to be fairly low impact, other fruits and vegetables are a little bit higher, dairy and cheese are higher still, chicken is then higher, and then some types of fish, and so on and so forth on up to beef. Those general principles hold in most environments, but once you get more specific than that, it’s really hard to make educated decisions as a consumer.
E.G.: I hate to even ask, but how is it that organic farming can emit more carbon?
Z.A.: Pesticides and industrialized agricultural practices enable greater production efficiency, by which I mean increasing the crop yield per acre of land. But that comes at the expense of many other things, and I’m not an expert in the many adverse impacts the use and overuse of fertilizers and pesticides can have on our water system and on nitrogen cycles, and those are important to consider. Climate and reducing greenhouse gas emissions is not the only thing that’s important here, all the other environmental impacts are essential to consider as well. I am by no means saying people should take a message that organic isn’t always better than non-organic in terms of gas emissions and take that to mean they shouldn’t eat organic.
E.G.: In terms of the way we are producing food right now, what does a low-carbon diet look like?
Z.A.: One of the really great things I was thrilled to learn, and that was consistently reinforced throughout the literature I reviewed, was that a low-carbon diet looks a lot like what nutrition experts define as a healthy diet. In fact, for the Project Drawdown report, we may actually call this solution a “healthy diet” rather than a “low-carbon diet” because they seem to basically be the same thing.
In practice, what that means is that you’re eating more vegetables, less animal products and less processed food. You’re also not eating too much. There are three ways to think about reducing the impact of our dietary choices. One is choosing fresh food and foods that tend to be low impact, according to the general hierarchy – which is that some foods just tend to be lower impact than others.
The second is not eating more than you need to sustain yourself, and that’s something that people don’t often talk about in this context, but that can make a big difference. If you’re in the habit of overeating by say, 20 percent, and then you just go back to eating what you need, you’ve saved a substantial amount of emissions by making a choice that’s also going to make you healthier.
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The third is the trickiest one, which I sort of mentioned already why it’s tricky, but choosing specific foods from low-carbon sources. If you’re choosing one potato versus another potato, then choosing the potato with a lower carbon impact, but like I said, that can be very hard to do in an informed way as a consumer.
E.G.: Have you switched to a low-carbon diet yourself?
Z.A.: Yes, I have. I’m not a perfect angel when it comes to low-carbon diet, but I do make a strong effort. I was a strict vegetarian for almost four years, up until about two years ago, and since January 2014, I’ve adopted a diet I describe as 98 percent vegetarian, wherein I basically cook vegetarian at home, when I go out to a restaurant I order vegetarian food, but if I am guest in somebody’s home and they’re cooking meat, or if I am traveling and I want to taste a particular regional specialty – like I went to Texas for the first time a year ago; I couldn’t leave without tasting Texas barbecue, so I make exceptions for those sorts of things.
It’s essential that folks understand that even though we do need to make very substantial changes to our dietary choices, these choices don’t mean we can’t eat one food or another, but it does mean we do need to eat less of some foods. In general, no foods are going to be off the table entirely, but we’re going to need to do a very substantial amount of moderation, assuming that we don’t find some sort of magic formula that lets us produce any kind of food that we want with negligible impact. Right now Americans eat almost a quarter-pound of beef every day on average. That’s one cheeseburger every day. So people like me, who eat one cheeseburger on average maybe every year, are offset by people eating two cheeseburgers a day on average. And that’s a totally unsustainable level that’s going to need to get down to maybe a cheeseburger a week, maybe more like a cheeseburger a month. Maybe less than that; it’s hard to say.
*Updated to add a link to a May 2017 article about the book "Drawdown."
